Contact element with crimp section

ABSTRACT

To reduce the risk of breakage and yet ensure good electric and thermal conductivity, pull-off strength and long service life of the connection, when connecting a contact element to a conductor (1) by crimping, the inner surface of the crimp section (6), in contact with the conductor (1), is provided with deformations that are grooves (2) and ribs running crosswise and obliquely to the longitudinal axis of the conductor (1).

FIELD OF THE INVENTION

The present invention relates to a contact element with a crimp sectionfor conductors, with deformations on the inner surface of the crimpsection provided for contact with the conductor.

BACKGROUND INFORMATION

Electric wires and cables with such contact elements, which exist innumerous forms as cable lugs, receptacles, or clamps, are used indifferent apparatuses and systems. Such contact elements allow areliable and detachable electric connection to be quickly established.The advantage of crimp connections is that wires can be connected to thecontact element using machines, resulting in a sufficiently stable,conductive connection between wire and contact element.

Efforts have continued to be made, however, to improve the connectionbetween the electric conductor and the contact element concerning itselectric and thermal conductivity, pull-off strength, service life, andresistance to corrosion so that it can withstand the effects of impacts,temperature fluctuations, moisture, corrosive atmospheres, or otherextreme conditions. This would allow such connections to be used in newapplications and make their operation in existing applications morereliable.

Thus, with conventional contact elements, there are depressions on theinside of the crimp section, which is in tight contact with the wire orwire bundle after crimping. The wire is deformed during crimping andpressure is applied to the depressions, providing improved mechanicalattachment. At the same time, corrosion layers and lacquer-typeinsulating material is removed from certain areas thus deformed of thewire surface. In most conventional contact elements, these depressionsare grooves running perpendicularly to the longitudinal axis of thewire. With the webs between the grooves, crimping produces a pluralityof annular channels on the wire. Thus, after crimping, the wire has asmaller diameter in the area of the annular channels and the risk of thewire being broken increases, which is obviously undesirable.

As described in U.S. Pat. No. 3,892,459, as many as possible smalldepressions are provided on the inside of the crimp section in othercontact elements to obtain as large a contact surface as possible. This,however, has the undesirable result that the small depressions on theside walls of the crimp section are closed due to the deformation of theside walls before the wires can be pressed into the depressions. U.S.Pat. No. 3,892,459 therefore describes that small, approximately squaredepressions may be provided on the bottom of the crimp section, which isonly slightly or not at all deformed during crimping, and largerlongitudinal depressions be provided on the side walls. The longerdimension of these longitudinal depressions extends perpendicularly tothe longitudinal axis of the wire. Thus also in this case annularchannels are formed on the wire, resulting in the aforementionedweakening of the wire and an increase in the risk of wire breakage.

U.S. Pat. No. 3,989,339 describes another conventional crimpedconnection using oblique channels and ribs.

Advantages of the invention

Upon crimping, each web between the grooves or each rib on the innersurface of the crimp section leaves a helical groove on the wire. Thusthe cross section of the wire is reduced uniformly in comparison withthe annular grooves in each longitudinal position located in the crimpsection as compared to the conventional arrangement. The contact surfacebetween contact element and wire is, however, much greater than that ofthe conventional contact element. This contact surface between contactelement and wire can also be further increased by increasing the numberof grooves and ribs, thus reducing the risk of breakage compared to theknown crimp connections between contact element and conductor. With theincrease in the contact surface, the electric and thermal conductanceand, in particular, the mechanical strength are improved due to thecrosswise arrangement of ribs and grooves. A preferable distribution ofthe reduction in the conductor's diameter is achieved when the groovesand ribs are arranged obliquely or helically in parallel to one another.

SUMMARY OF THE INVENTION

To increase the contact surface between crimp section and conductoraccording to this invention, two groups of grooves and ribs are providedobliquely to the longitudinal axis of the conductor as deformations, thegrooves and ribs of one group running obliquely to those of the othergroup. The grooves and ribs of each group run parallel to one anotherand the grooves and ribs delimit diamond-shaped elevations anddepressions, i.e., the grooves and ribs intersect one another at acuteor obtuse angles that are preferably not equal to 90°.

The diamond-shaped elevations can preferably capped by pyramid-shapedvertices.

A further embodiment of the contact element according to the presentinvention is the use for insulated wires, in particular varnished wireswith no prior insulation of the ends to be connected. By pressing thewire or the wires of a wire bundle into the grooves or the gaps betweenthe ribs, the insulating layer or the varnish layer, and in addition anycorrosion layer, is scraped off or pressed away by cutting into thesharp-edged linear elevations or by the vertices of the diamond-shapedelevations penetrating into the wires, and a good contact between wireand contact element is ensured. The operation of insulating can beomitted. Due to the crimped state of the grooves running helically, thematerial scraped off is removed to the outside at the time of crimpingas it would be by a drill, and the bond between crimp section and wireis sealed at the edge of the crimp section, providing protection againstthe penetration of corrosive gases or liquids.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional contact element prior to crimping.

FIG. 2 shows a detailed cross section through a crimp section enclosinga wire after crimping for the contact element illustrated in FIG. 1.

FIG. 3 shows the cross-section of a wire along III--III illustrated inFIG. 2.

FIG. 4 shows another conventional contact element prior to crimping.

FIG. 5 shows a cross-section through a crimp section of a contactelement illustrated in FIG. 4 enclosing a wire after crimping.

FIG. 6 shows the cross-section of the wire along VI--VI illustrated inFIG. 5.

FIG. 7 shows a projection of a first crimp section embodiment of acontact element according to the present invention with a first group ofparallel grooves and a second group of parallel countergrooves runningobliquely to the grooves of the first group.

FIG. 8 shows a side view of the crimp section illustrated in FIG. 7after crimping without showing the conductor, the dashed linesrepresenting one of the grooves and one of the countergrooves inside thecrimp section.

FIG. 9 shows another embodiment according to the present invention,which is manufactured by simple embossing or rolling or pressing fromthe back side.

DETAILED DESCRIPTION OF THE INVENTION

Detailed Description of the Exemplary Embodiment

FIG. 1 shows a conventional contact element prior to crimping with aconductor 27. At one end, the contact element has a plug-and-socketconnector part 25, which can be pushed onto a flat contact plate to wirea machine or a part of a system. At the other end of the contactelement, a crimp section 26 is provided, which has depressions in theform of grooves 33 extending perpendicularly to the longitudinal axis 34of the conductor on its inner surface. Conductor 27 can be a single,solid wire or a braided cable and is pushed in the direction of arrow 28into crimp section 26. Then crimping is performed, during which sidewalls 29, 30 of crimp section 26 are bent in the direction of arrows 31,32. Conductor 27 is also deformed during crimping, being primarilypressed into grooves 33 and displaced by webs 35 between grooves 33.Webs 35 form annular grooves 36 on the conductor surface and thus reducethe conductor cross section in this area. FIG. 2 clearly shows annulargrooves 36, produced by webs 35. FIG. 3 shows the section of theconductor in the area of an annular groove 36.

FIG. 4 illustrates another conventional element. A conventionalplug-and-socket connector part 5 is provided as a connecting option.Ribs 2, running obliquely to the longitudinal axis 14 of conductor 1,are provided on the inside of crimp section 6. If conductor 1 is pushedinto crimp section 6 in the direction of arrow 8, and side walls 9, 10of crimp section 6 are bent according to arrows 11, 12, ribs 2 separatedby webs 15 form helical grooves 16 on the surface of conductor 1, thematerial of conductor 1 being displaced by the pressure applied duringcrimping toward webs 15 between ribs 2. The insulation or corrosionlayers on the surface of the conductor may be scraped off due to thedeformation of the conductor during crimping, so that a good electricand heat-conducting contact is created between conductor 1 and thecontact element. The scraped-off insulation material or corrosionproduct is pressed outward in helical grooves 16 and seals the contactarea between conductor 1 and crimp section 6 of the contact elementagainst the penetration of corrosive gases and liquids. FIG. 5 showsgrooves 16 running obliquely on the surface of wire 1. The cross sectionof conductor 1 shown in FIG. 6 is reduced to a much lesser degree thanthe cross section of the conductor illustrated in FIG. 3 in the area ofan annular groove.

FIGS. 7-9 show two embodiments of a crimp section according to thepresent invention. In the embodiment illustrated in FIG. 7, which showsa projection of crimp section 56 of a contact element from the inside,the inside surface of crimp section 56 has a group of grooves 53 and asecond group of countergrooves 54. The grooves and countergrooves ofeach group run parallel to one another and both grooves 53 andcountergrooves 54 run obliquely to the direction of insertion (arrow 58)and thus to the longitudinal axis of the conductor. As shown in FIG. 7,grooves 53 and countergrooves 54 form acute and oblique angles with oneanother, delimiting diamond-shaped elevations 55, which produce similardiamond-shaped depressions in the conductor during crimping. For reasonsof strength, angles not close to 90° between grooves 53 andcountergrooves 54 are preferred. FIG. 8 shows a side view of crimpedcrimp section 56. A groove 53 and a countergroove 54, running helicallyon the inside of the crimp section, are shown in dashed lines.

FIG. 9 shows elevations embossed crosswise in the form of diamond-shapedpyramids 75, with which the insulation layer can very easily bepenetrated through high-pressure surface pressing. Elevations 75 aredelimited by grooves 73, 74 running obliquely to one another and to thedirection of insertion 78, grooves 73, 74 being flush with edge 79 ofthe crimp section.

What is claimed is:
 1. A contact element comprising:a crimp section having an inner surface; and deformations at the inner surface of the crimp section for contacting a conductor, the deformations including two groups of grooves and ribs, each of the two groups of grooves and ribs extending across the inner surface obliquely to a longitudinal axis of the conductor, wherein a first group of the two groups of grooves and ribs extends across the inner surface in a first direction, a second group of the two groups of grooves and ribs extending across the inner surface in a second direction and intersecting on the inner surface with the first group, the first direction being oblique to the second direction.
 2. The contact element according to claim 1, wherein the grooves of one of the two groups extend parallel to the ribs of the one of the two groups.
 3. The contact element according to claim 1, wherein the grooves are indented in the inner surface.
 4. The contact element according to claim 1, wherein the grooves and the ribs of the two groups form diamond-shaped elevations and depressions.
 5. The contact element according to claim 4, wherein the diamond-shaped elevations are capped by vertices.
 6. The contact element according to claim 5, wherein the vertices have a shape of a pyramid. 